The present invention relates generally to optical fibers, and more specifically to techniques for determining the characteristics of an optical fiber that is coupled to a connector such as a connector on a radiation source.
Optical fibers have the desirable characteristic of being able to transmit light coupled into a first end of the fiber to a remote location at the second end of the fiber. Transmission is for most practical purposes substantially lossless, and the second end of the fiber can be moved about at will since the fiber is highly flexible. One example of a medical application is directing a laser's infrared radiation into the first end of an optical fiber, the second end which is inserted into a patient's eye, and causing the light emerging from the second end of the fiber to illuminate or deliver surgical energy for photocoagulation of a small area on the patient's retina.
The fiber is typically encased within a protective sheath and terminates at its first end in a connector. The connector, when it engages a complementarily configured connector on a fixed structure, holds the first end of the fiber at a defined location relative to the fixed structure. In this case, the fixed structure is the optical bench within a cabinet that houses a laser and suitable optics for coupling the laser output beam to the fiber.
One type of connector, referred to as an SMA-style connector, includes a ferrule and a cable nut rotatably mounted to the ferrule. The ferrule has an open end for insertion of a sheathed fiber, and a second end, closed except a precisely centered bore sized to accommodate the unsheathed end of the fiber. The fiber end is cemented into the ferrule. A complementary connector includes an externally threaded bushing sized to accommodate the ferrule and engage the cable nut.